The invention relates to a method of compensating eddy current effects in a magnetic resonance apparatus in which a signal for eddy current compensation is derived from a non-compensated gradient control signal, and also relates to an apparatus comprising means for eddy current compensation via gradient control signals.
A method and apparatus of this kind are known from EP No. 215 547 corresponding to U.S. Pat. No. 4,703,275 This document describes a method of eddy current compensation where the gradient field generated via a non-compensated gradient control is measured and compared with a desired gradient field, a signal being derived from the comparison in order to compensate the gradient field control signal. For carrying out this method it is necessary to include additional measurement coils in the apparatus or a gradient coil to be used for imaging must be suitable for performing the measurements. Additional measurement coils, however, themselves may have an effect on the eddy current behaviour and must be accurately positioned in the apparatus, and customary gradient coils produce comparatively inaccurate measurement results. Moreover, deviations from the desired gradient fields are also measured, while the consequences thereof for diagnostic measurements of resonance signals are of primary importance.